Process for preparation of stretch yarn



Oct. 29, 1963 TAKATOSHI KOBAYASHI PROCESS FOR PREPARATION OF STRETCH YARN Filed Feb. 15, 1961 Fig.

Fig. 2

INVENTOR TA nnrasul Kama A'I'I'ORNEY United States Patent PRQCESS FOR PREPARATION OF STRETCH YARN Taliatoshi Kobayashi, Suginami-ltu, Tokyo, Japan, as-

signor to Toyo Rayon Kahushiki Kaisha and Toyo Nylon Nenshi Kako Kabushiid Kaisha, Tokyo, Japan,

both corporations of Japan Filed Feb. 15, 1961, Ser. No. 89,521 Claims priority, application Japan Feb. 25, 1960 Claims. (Cl. 57157) This invention relates to process for imparting stable crimp, ree of twisting tendency, to thermoplastic, organic textile fiber such as of polyamide, polyester, polyolefin, polyacrylonitrile and acetate.

The preparation of bulky stretch yarn from synthetic fibers by the steps of high twisting, heat setting, and untwisting has been known. The stretch yarns manufactured by that process not being completely removed of the twist, they are widely used as doubled yarn wherein an S-direction yarn and a Z-direction yam are interentwined so that the twisting tendency of the two yarns each to opposite direction is off-set.

As the method of preparing stretch yarn which is free of twisting tendency and can be used without doubling,

Japanese patent application of Heberlein und Kompanie Aktiengesellschaft of Switzerland, published in O-fficial Patent Gazette (of the Japanese Patent Oil-ice) under Publication No. 1000 of 1958, disclosed a method of preparing permanently crimped yarn from organic synthetic textile fiber which comprises firstly high-twisting the yarn, heat setting the yarn as imparted with the high twist with wet or dry heat, untwisting the yarn to the normal twist, again high twisting the yarn to the opposite direction from the first high twist, heat setting the yarn with wet or dry heat, and thereafter unt wisting the yarn to the normal twist.

However the above method is mainly useful for finest denier multi-filarnent yarn, and if applied to yarns, particularly so called large denier multi-filament yarns, for instance, having a denier of above 200, the product tends to be unduly strained for the later explained rea sons and in the practical purpose, is not substantially different from that obtained from the first cited process comprising high twisting, heat-setting and untwisting. Therefore said method of the Heberlein company is of little use for large denier yarns.

Accordingly the object of the present invention is to provide a process for preparing stretch yarns free of twisting tendency, which is useful not only for very fine denier yarn, but also is capable of even finishing of the yarn of normally used deniers, for instance 300 deniers or more.

Another object of this invention is to provide stretch yarns of high bulk, free from twisting tendency and which, upon comparing with heretofore known twisted stretch yarns, have soft touch, excellent feel and handling properties, regardless the size of the denier of the yarn.

Still another object of this invention is to provide stretch yarns which are free of twisting tendency and have, as well as the soft hand and high bulk, an increased uniform dyeability.

The further objects of this invention shall be made clear from the following descriptions.

FIGURE 1 is a diagrammatic showing of the process of this invention, and

FIGURE 2 is a diagrammatic showing of the twisting moment given to the yarn in accordance with the proc ess of this invention.

According to the present invention the foregoing objects and advantages are accomplished by the process comprising twisting multi-filarnent yarn of thermoplastic 3,108,430 Patented Oct. 29, 1963 organic textile fiber, heat setting the same, thereafter untwisting it to the normal state, subjecting it to the second heat setting under a suitable tension, re-twisting it to the opposite direction from that of the first twisting, heat setting the same, untwisting it again to the normal state and thereafter subjecting it to the fourth heat setting with or without tension. The term normal state as employed herein in the specification and claims is meant to refer to an S or Z-twist on the order of about 10-300 t./m. imparted to a yarn to prevent the separation of the filaments of the yarn.

In practicing the present invention, for instance if a throwing machine is used, firstly the yarn is subjected to high twisting, the first heat setting, and untwisting to the normal state, and thereafter, to the second heat setting as wound up on the cylinder, or as re-wound onto the cylinder so that the tension exerted on the yarn is maintained uniform. At this time the internal stress of the fiber is completely eliminated and the remaining twisting tendency in the yarn is made zero.

Subsequently the ymn is again subjected to another high twisting to the opposite direction, third heat setting, untwisting to the normal state, and then to the fourth heat setting as wound up on the cylinder, or re-wound onto the cylinder maintaining the uniform tension of the yarn, or in the form of a bank. By this last heat setting the yarn is completely eliminated of the internal stress of the fiber, and has zero twisting tendency.

In case false twist machine is utilized, besides the heating apparatus provided on the way to the spindle for false twist, second heating apparatus is provided before the wind-up cylinder, thereby giving the second heat setting to the yarn which has been untwisted by said spindle for false twist. The yarn leaving the second heating apparatus is then wound up onto the cylinder. Thereafter the yarn is passed through a similar false twist machine so as to be imparted twist to the opposite direction from that of the first twist, thus subjected to twisting, the third heat setting, untwisting and the fourth heat setting before wound up onto the cylinder.

Alternatively said second false twist machine may be omitted of the second heating apparatus, and the yarn wound up onto the cylinder may be subjected to the fourth heat setting in a hank form. Or, the first false twist machine may be omitted of the second heating apparatus. Then the yarn is given the second heat setting by another heat setting apparatus in advance of the second twisting in the false twist machine.

If the above process of this invention is shown'diagrarnmatically, itwi-ll be as in attached FIG. 1. The twisting moment given to the yarn in each of the above steps of the present invention draws the diagram of twisting moment in (I), by the treatments of each first high twisting, first heat setting, first untwisting, second heat setting, from the starting point A shown in FIG. 2 to AB-BC-CD-DE (':,DA), and then by the treatments given to the opposite direction from that of the first series, that is, the second twisting, the third heat setting, the second untwisting, and the fourth heat setting, draws the diagram of twisting moment in (II), as E A ")F"GGH'H'1 In contrast to this, when the aforesaid crimping finish of Heberlein company is practiced, the twisting moment of the yarn draws the diagram of twisting moment as ABBCCDF'F'G-GH.

Before the actual results were obtained, it was presumed that by the treatments of the present invention, the twisting moment of the yarn would draw a diagram as However the actually obtained results of the experiments proved contrary to such anticipation, but showed surprising fact that in this invention, (a) a very great twisting moment such as EF is given to the yarn by the second twisting; (b) in spite of the exerting of such a great twisting moment, by the third heat setting, even if carried out under the same conditions as employed for the second heat setting in the method of Heberlein company, the twisting moment is decreased to approximately equal to that of the yarn in the Heberlein method; and (c) as shown by point H, the twisting moment exerted on the yarn after the second untwisting is smaller than the twisting moment of the yarn which has been twice untwisted in accordance with the Heberlein method (shown by point H).

That in the process of this invention such a great twisting moment can be given to the yarn by the second twisting as referred in (a) above, is due to such factors as, in the second heat setting step the yarn of zero twist being heat set as stretched by tension, the internal stress of the fiber has been completely removed, and the forms of the filaments of inner and outer layers of the multifilament yarn are made uniform coils. This also means that in the second twisting step the yarn is imparted effective twisting condition for receiving the third heat setting of the subsequent step. A further advantage of the second heat setting is to enable the decrease in twisting moment after the second untwisting of the yarn as above described, and to facilitate the fourth heating treatment.

Again the results of (b) and above indicate that the third heat set-ting and the fourth heat treatment can be carried out easily and smoothly, and moreover mean that the process of this invention may be practiced. on an industrial scale with stability.

The conspicuous superiority of the products of this process over the products of conventional processes is thus resulted from the fact that after the second heat setting and the fourth heat treatment, the twisting moment of the yarn at normal twist is returning to the starting point A, that is, substantially zero, indicating that the internal stress is completely removed.

The second and fourh heat setting of the present invention is particularly important. For example, particularly in the knitted goods of large denier yarns such as of 300 deniers or 200 deniers, if the second heat setting and the fourth heat treatment as shown in FIG. 1 are omitted, the knitted goods therefrom is greatly biased, and commercially valueless, and also if the second heating only is omitted, the knitted goods still shows some bias, and moreover tends to change the bias after a hot water treatment. Thus the product has inferior commercial value. On the other hand, the knitted goods of the product yarn which has been subjected to the second heat setting and the fourth heat treatment in accordance with the present invention show substantially no bias, and are not biased by hot water treatment.

A more surprising advantage is that by the present invention stretch yarn is obtained which, when finished to knitted goods, is far superior to other goods in soft touch, excellent feel and handling properties, and uniform dyeability.

As shown in the above, the second heat setting has a different importance from that of the fourth heat treatment. By this second heat setting, as already mentioned, the orientation of crystal within the yarn is bettered as well as the uneven spiral form is made uniform, thereby the slippage among the monofilaments is improved, and the yarn as the whole is substantially removed of the internal stress. The stage (I) of this process is completed then, and stage (II) follows. The elimination of the stress in the yarn assists the highly effective operation of stage (II) subsequent to the second twisting, working together with the decrease in the twisting moment by the second heat setting.

Furher the practice of the second heat setting and the fourth heat treatment is useful to increase the bulk and particularly to make up the fine, soft touch of the knitted and woven fabrics thereof.

Again in the present invention, by carrying out the fourth heat treatment after the second untwisting, the unevenness of the coils or crimp is corrected, and the finished product having excellent uniformity is obtained.

In this invention, the twisting moment at the second twisting is increased by the effect of the second heat setting, however the third heat setting requiring no particularly complicated conditions, the number of twist in the second twisting (T is not necessarily limited by the condition of T T (number of twist in the first twisting).

Thus the present process for the preparation of stretch yarn is extremely stable, and has a surprising superiority in comparison with heretofore known processes.

The above shall be explained hereinbelow as to examples.

Example 1 Nylon yarn of 210 d./ 15 fil. was high-twisted by a throwing machine at 1950 t./m. (S-direction), subjected to first heat setting by saturated steam of 118 C. for 20 minutes, untwisted to normal state, re-wound onto the cylinder under a tension of approximately 20 g., and thereafter subjected to the second heat setting with saturated steam of 106 C. for 10 minutes.

Then the yarn was given a high twist by a throwing machine at 1400 t./m. (Z-direction), subjected to the third heat-setting with saturated steam of 110 C. for 10 minutes, over-untwisted at r t./m. (S-direction) and thereafter heat treated in the form of a hank with saturated steam of 115 C. for 15 minutes, that is, the fourth heat treatment.

Example 2 Nylon yarn of 210 d./ 24 fil. was temporarily high twisted by a false twist machine at 2000 t./m. (S-direction), and first-heat set by a heated plate (hereafter referred to as the first heater) provided between the discharge apparatus and the spindle for false twist at 160 C. for 0.6 second. The yarn untwisted by said spindle for false twist was second-heat set by the heated plate (hereinafter referred to as the second heater) provided between the spindle for false twist and the wind-up device at C. for 0.5 second under a tension of 20 g. and wound up onto a bobbin. Then this yarn was again temporarily high twisted by the second false twist machine at 1500 t./m. (Z-direction), and subsequently third-heat set by the first heater at C. for 0.6 second.

This yarn, after untwisted by a spindle for false twist, was further subjected to the fourth heat treatment by the second heater at 140 C. for 0.5 second, and wound up onto a bobbin.

Example 3 Nylon yarn of 300 d./40 fil. was high-twisted by a throwing machine at 1600 t./m. (S-direction), first-heat set with saturated steam at 120 C. for 20 minutes, which was then untwisted to the normal state under the tension of 25 g., and second-heat set with saturated steam at 110 C. for 10 minutes. This yarn was temporarily high-twisted by a false twist machine at 1600 t./m. (Z- direction), third-heat set by the first heater at C. for 0.8 second, and then was made into the form of a hank to be subjected to the fourth heat treatment with saturated steam of 115 C. for 15 minutes.

Example 4 Nylon yarn of 2 10 d./24 fil. was high-twisted by a throwing machine at 2000 t./m. (S-direction), first-heat set with saturated steam of 120 C. for 20 minutes, subsequently untwisted to the normal state to be wound up onto the cylinder under a tension of approximately 20 g. and second-heat set with saturated steam of 108 C. for 10 minutes. This yarn was again high-twisted by a throwing machine at 2500 t./m. (Z-direction), and after the third heat setting with saturated steam of 112 C. for 10 minutes, over-untwisted at 1120 t./m. (S-direction), wound up onto the cylinder and fourth-heat set with saturated steam of 116 C. for 20 minutes.

Example 5 Polyethylene terephthalate yarn of 100 d./48 fil. was given a temporary high twist by a false twist machine at 2600 t./m. (S-direction), the first heat setting by the first heater at 210 C. for 0.6 second, untwisting by the spindle for false twist, and further the second heat setting by the second heater at 180 C. for 0.5 second under the tension of 15 g. The yarn was then wound up onto a bobbin. Again this yarn was given a temporary high twist by the second false twist machine at 1600 t./m. (.2- direction), the third heat setting by the first heater at 210 C. for 0.6 second, untwisting by the spindle for false twist and then the fourth heat treatment by the second heater at 180 C. for 0.5 second. Finally the yarn was wound up onto a bobbin.

The products obtained by the above examples were all free of twisting tendency, have soft touch, excellent feel and handling properties, and high bulk.

The above examples illustrate only some modes of practicing the present invention, and this invention is by no means thereby limited. For instance, the yarns to be employed may be composite yarns, for example, that of Nylon yarn of 210 d. and that of 70 d. intertwined together, and of course may be those of different types of yarns bundled together. Also naturally the first, second, third heat setting and the fourth heat treatment can be accomplished by the same means, for example electrically heated plate, heated air, or by wet heat, or these means may be used in combination.

The foregoing explanations having been given as to multifilament yarns, the present invention is similarly applicable to monofilament yarns.

It is also permissible to impart low twist to the material yarn, for example, by a throwing machine, in advance of subjecting the yarn to a false twist machine.

What I claim is:

1. Process for preparation of a thermoplastic, organic textile stretch yarn which comprises subjecting the yarn to high twisting, heat setting, and untwisting to a normal state, heat treating the untwisted yarn of normal state under tension, ifurther subjecting the yarn to a high twisting in the opposite direction, heat setting and untwisting to a normal state, and thereafter again heat treating the untwisted yarn of normal state.

2. Process according to claim 1, wherein the material yarn is monofilament yarn.

3. Process according to claim '1, wherein the material yarn is multifilament yarn.

4. Process according to claim 1, wherein the material ymn is a composite yarn consisting of at least two strands of yarns.

5. Process according to claim 4, wherein the yarns composing the composite yarn are different types of thermoplastic, organic textile strands.

6. Process according to claim 1, wherein the first high twisting and the second high twisting are effected by a throwing operation.

7. Process according to claim 1, wherein the first high twisting and the second high twisting are etlected by a false twist operation.

8. Process according to claim 1, wherein the first high twisting is effected by a throwing operation and the second high twisting is eflected by a false twist operation.

9. Process according to claim 1, wherein the first high twisting is eiiected by a false twist operation and the second high twisting is effected by a throwing operation.

10. Process according to claim 1, wherein the heat setting and the heat treatment is efiected by the source of heat selected from the group consisting of heated air, heated steam and electricity.

References Cited in the file of this patent UNITED STATES PATENTS 2,304,089 Heberlein Dec. 8, 1942 2,662,558 Mersereau et al Dec. 15, 1953 2,869,318 Stucki Ian. 20, 1959 3,022,565 Fitzgerald Feb. 27, 1962 FOREIGN PATENTS 817,771 Great Britain Aug. 6, 1959 

1. PROCESS FOR PREPARATION OF A THERMOPLASTIC, ORGANIC TEXTILE STRETCH YARN WHICH COMPRISES SUBJECTING THE YARN TO HIGH TWISTING, HET SETTING, AND UNTWISTING TO A NORMAL STATE, HEAT TREATING THE UNTWISTED YARN OF NORMAL STATE UNDER TENSION, FURTHER SUBJECTING THE YARN TO A HIGH TWISTING IN THE OPPOSITE DIRECTION, HEAT SETTING AND UNTWISTING TO A NORMAL STATE, AND THEREAFTER AGAIN HEAT TREATING THE 